The invention relates generally to a method for producing a bundle of paper sheets, especially of folded printed sheets.
As a rule, sheets are delivered by a rotary machine in an overlapping sheet-by-sheet stream. In order to make the flow of material between the rotary machine and, for example, a bookbinding machine, more economical, discrete stacks are formed from the folded sheets of the sheet-by-sheet stream, which stacks are strapped into bundles. After intermediate storing, the bundles are delivered to the bookbindery for further processing. For the purposes of this description, "stacks" consist of signatures while the bundle represents a strapped or banded stack.
In a well-known device, columns are formed from the sheet-by-sheet stream by means of a hold-back mechanism. The columns are moved from a horizontal transport position vertically downward toward a conveyor belt system running horizontally. The paper sheets of the columns, which stand vertical and reach the conveyor belt system, are jogged by means of conveyor belts and a contact a pressure band between two spacing elements and are gathered in series; here the spacing elements can support guard plates. The formation of columns should produce a gap which enables a spacing element to swing thereinto to define the end of the series. The gathered series is moved upward, gripped and compressed, transported laterally into a banding station and provided with a bundling strip in order to form the bundles.
This well-known device requires a large number of machine elements and very much space. Especially the vertical position of the sheets causes considerable disadvantages for the gathering operation. For instance, the paper sheets bulge outward close to the spacing elements so that it becomes impossible to slide in the guard plates, which are supposed to protect the bundled bundles during the transport aand the storing for further processing. This problem can be met only by means of an expensive additional device. Aside from the described disadvantages, the conveyor belts for moving the sheet-by-sheet stream cause friction at the gathering spot especially in the zone of transfer to the conveyor belt running horizontally; such friction leading to a smearing of the printing color and perhaps destruction of the sheet.